In this March 13, 2017, photo, Massachusetts paper conservator Seth Irwin works at the Alaska State Museum on the Sesquicentennial documents that will go on display later this year at the State Library, Archives and Museum in Juneau, Alaska. (Michael Penn /The Juneau Empire via AP)

Robert Mueller’s special counsel investigation into Russian meddling in the 2016 election has cost $6.7 million during the first four and a half months of the probe. Click to see past independent counsel investigations guilty of racking up high bills.